title: Influence of the forest caterpillar hunterCalosoma sycophantaon the transmission of microsporidia in larvae of the gypsy mothLymantria dispar.
abstract: The behaviour of predators can be an important factor in the transmission success of an insect pathogen. We studied howCalosoma sycophantainfluences the interaction between its prey [Lymantria dispar(L.) (Lepidoptera, Lymantriidae)] and two microsporidian pathogens [Nosema lymantriae(Microsporidia, Nosematidae) andVairimorpha disparis(Microsporidia, Burellenidae)] infecting the prey.Using laboratory experiments,C. sycophantawas allowed to forage on infected and uninfectedL. disparlarvae and to disseminate microsporidian spores when preying or afterwards with faeces.The beetle disseminated spores ofN. lymantriaeandV. dispariswhen preying upon infected larvae, as well as after feeding on such prey. Between 45% and 69% of test larvae became infected whenC. sycophantawas allowed to disseminate spores of either microsporidium.Laboratory choice experiments showed thatC. sycophantadid not discriminate betweenNosema-infected and uninfected gypsy moth larvae. Calosoma sycophantapreferredVairimorpha-infected over uninfected gypsy moth larvae and significantly influenced transmission.WhenC. sycophantawas allowed to forage during the latent period on infected and uninfected larvae reared together on caged, potted oak saplings, the percentage ofV. disparisinfection among test larvae increased by more than 70%. The transmission ofN. lymantriaewas not affected significantly in these experiments.Beetles never became infected with either microsporidian species after feeding on infected prey.We conclude that the transmission ofN. lymantriaeis not affected. Because noV. disparisspores are released from living larvae, feeding on infected larvae might enhance transmission by reducing the time to death and therefore the latent period.
authors.affiliation: Department of Forest and Soil Sciences, BOKU-University of Natural Resources and Life Sciences Hasenauerstraße 38, 1190 Vienna.
authors.forename: Dörte
authors.initials: D
authors.lastname: Goertz
authors.forename: Gernot
authors.initials: G
authors.lastname: Hoch
keywords: Carabidae; Lymantriidae; Nosema lymantriae; Vairimorpha disparis; host–pathogen interaction; predation; transmission